Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J37/00—Discharge tubes with provision for introducing objects or material to be exposed to the discharge, e.g. for the purpose of examination or processing thereof
  • H01J37/32—Gas-filled discharge tubes
  • H01J37/32009—Arrangements for generation of plasma specially adapted for examination or treatment of objects, e.g. plasma sources
  • H01J37/32055—Arc discharge
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2237/00—Discharge tubes exposing object to beam, e.g. for analysis treatment, etching, imaging
  • H01J2237/02—Details
  • H01J2237/022—Avoiding or removing foreign or contaminating particles, debris or deposits on sample or tube

Definitions

• the invention relates to devices and methods for coating substrates in a vacuum, a plasma being generated from a target and ionized particles of the plasma being deposited on the substrate as a layer, as has been used successfully for a long time in the various known PVD methods becomes.
• the invention is a supplement to the so-called laser-are method, in which an arc discharge is ignited in a vacuum by means of a pulsed laser beam and the ionized particle stream is guided to a substrate on the plasma obtained via the arc discharge and on this substrate as a layer the ionized particles can be deposited, applicable.
• the invention can also be used in a method known per se, in which an arc charge in vacuum is used to generate the plasma without the arc discharge being initiated with a laser beam.
• the arc discharge can be ignited in a known manner, either solely by a sufficiently high voltage between an anode and a target connected as a cathode, and on the other hand there is the possibility of initiating the ignition by means of electrically conductive ignition elements as a result of a short circuit.
• Another possibility in which the solution according to the invention can be used sensibly is the generation of a plasma on a target by loading Radiation of the target surface with a laser beam of sufficient intensity.
• the construction of these systems is very complex and accordingly expensive.
• the diameter of the magnetic filter and thus the diameter of the coating area is limited to approx. 150 mm due to the strong magnetic fields and the electrical power required.
• the coating rate of the processes is reduced to approx. 15-20% compared to that without using the filter.
• the procedure according to the invention is such that an additional absorber electrode is used which is at an electrically positive potential with respect to the plasma and around which an electric field is generated. Ionized particles and electrons of a plasma are guided through this electric field and are achieved in that electrically negative particles are absorbed by the absorber electrode and positive particles, preferably with a low mass-to-charge ratio of the plasma, reach the substrate.
• the size of neutral particles and particles with a large mass-to-charge ratio are only slightly influenced and can thus be separated.
• Such an absorber electrode is much easier and cheaper to manufacture and operate than the known magnetic filter systems used.
• a particularly advantageous embodiment of the invention consists in using it in a device in which a pulsed vacuum arc discharge with a pulsed laser beam which is directed onto the surface of a target connected as a cathode is used.
• a pulsed vacuum arc discharge with a pulsed laser beam which is directed onto the surface of a target connected as a cathode is used.
• Such devices with the corresponding methods are described, for example, in DE 39 01 401 C2 and in an improved form in DD 279 695 B5.
• the vacuum arc discharge for generating a plasma is ignited between the target and an anode, and the ionized particles of the plasma are then subsequently deposited on a substrate as a layer.
• a wide variety of forms can be used for the formation of the anode and the target used, and a wide variety of target materials can be used.
• the invention can also be used in a device or in a method in which the plasma is generated exclusively by means of an arc discharge in a vacuum, as is described, among others, in DD 280 338 B5.
• the arc discharge is initiated either solely by increasing the voltage or in connection with the generation of a short circuit.
• a target connected as a cathode and an anode are used in a vacuum chamber, between which an arc, preferably pulsed, is ignited and a plasma is generated from the target material.
• an arc preferably pulsed
• the arc should be guided along the surface of the target using controllable magnetic fields.
• the absorber electrode is again arranged in the immediate vicinity of the target and / or the anode.
• An electric field is generated around the absorber electrode, the absorber electrode in turn being kept at an electrical positive potential with respect to the plasma, so that the positive particles of the particle stream are moved from the plasma towards the substrate and the layer is formed there. without the larger or more massive charged particles of the particle stream get to the substrate because they hit the absorber electrode and can be absorbed.
• the absorber electrode to be used according to the invention can also be used in a device or in a method in which the plasma is generated by a target with a laser beam which is directed onto it. Such a procedure is e.g. in US 4,987,007.
• a plasma can also be generated from a target material that is not conductive.
• the absorber electrode in the immediate vicinity of the base of the plasma, i.e. the focal point of the laser beam is placed on the target.
• the separation of the differently charged particles of the ionized particle stream is carried out in the form already described for the other possibilities, so that almost exclusively positively charged particles of the particle stream reach the substrate and form the layer there.
• the invention can advantageously be further developed by arranging or forming the absorber electrode and / or the substrate in such a way that no particles and ions from the plasma can reach the substrate directly.
• a shielding screen can also be used, which can be arranged accordingly between the target and the substrate.
• An element forming the absorber electrode should span a plane which is arranged, aligned and dimensioned such that the particle stream of the plasma cannot reach the substrate directly. In the simplest case, it can be a act on the inclined planar plane. However, a convexly curved plane can also be spanned.
• Such a level does not necessarily have to be a closed surface, but gapsy elements, such as Grids, perforated or slotted sheets or other structural elements are used.
• the effect of the absorber electrode used according to the invention is based on the high degree of ionization of the plasma, which can be achieved with the processes already mentioned without the ions having to have a high kinetic energy.
• the energy of the ions is between 30 and 100 eV.
• the degree of ionization of a plasma in a vacuum arc discharge is approximately 80 to 90%.
• the absorber electrode has the sole function of
• the absorber electrode By arranging the absorber electrode in the immediate vicinity of the anode or the target, a very large part of the electrons and negatively charged ions is absorbed and at the same time prevented by recombination processes that the degree of ionization of the ions significantly before leaving the absorber electrode in connection with the electric field trained deflection changes.
• the coating rate can be influenced positively, in which the absorber electrode, the substrate and the other components which may be necessary for the generation of the plasma are formed and / or arranged in a favorable manner. Particularly suitable embodiments will be described in more detail below.
• the absorber electrode With a corresponding shape of the absorber electrode, it can be achieved that when the plasma enters the electric field generated around the absorber electrode, the electric field vector is oriented orthogonally to the direction of movement of the ion current and so the kinetic energy of the ions is only slightly influenced. For this reason, almost exclusively the ions can be optimally redirected to the substrate as a positively charged space charge due to the effect of the electric field.
• the substrate heats up only to a very small extent, so that the actual coating process is carried out almost at room temperature, so that corresponding thermally sensitive substrates can also be coated without further ado.
• the energy of the ions and thereby also the properties of the layer formed can be influenced in a targeted manner by a negative voltage applied to the substrate.
• a lattice-shaped element made of an electrically conductive material between the base point of the plasma and the absorber electrode, through which the plasma is guided.
• a lattice-shaped element can be placed on the electrical potential of the anode.
• lattice-shaped elements ment curved in the direction of movement of the plasma.
• the grid-shaped element can be connected to the anode and, if appropriate, a screen used, and consequently also attached to it.
• the invention can advantageously also be used to form reactively influenced layers.
• gases can be added. These gases are ionized and chemically activated in the vicinity of the absorber electrode, so that with, for example, nitrogen, oxygen, H 2 , hydrocarbons, with a low mass flow and consequently very low gas pressures below 10 -1 Pa, for example oxidic, carbide or nitride Layers or a combination, such as carbonitrides can be generated.
• FIG. 1 shows an example of a device according to the invention in which a plasma is generated using a laser arc method and a curved absorber electrode is used;
• FIG. 2 shows an example of a device according to the invention, in which a plasma is generated using a laser are method and a curved absorber electrode formed from a plurality of strips is used;
• Figure 2a shows the example of Figure 2 in perspective;
• FIG. 3 shows an example of a device according to the invention in which a plasma is generated with a laser beam and a curved absorber electrode formed from a plurality of individual strips is used;
• Figure 3a shows the example of Figure 3 in perspective
• FIG. 4 shows an example of a device according to the invention with an absorber electrode formed from strip-shaped elements
• FIG. 5 shows an example of a device according to the invention with an absorber electrode formed from strip-shaped elements, in which the plasma is generated exclusively with a laser beam, and
• FIG. 6 shows a further example of a device according to the invention with an absorber electrode, the anode function for generating
• FIGS. 1 to 6 the vacuum chamber in which the individual components shown in the figures are accommodated was dispensed with at all, since it can be assumed that this is obvious to the person skilled in the art lies.
• a roller-shaped target 1 is used, which is rotated uniformly about its longitudinal axis.
• an anode 4 is used, which is preferably designed as an anode screen with a central gap through which the generated plasma can escape, as is the case in FIGS. 1 and 1 a and also in FIGS. 2 , 2a and 4 shown shape of the anode 4 is indicated.
• a laser beam 5 is directed in a pulsed form onto the surface of the target 1 and at the same time the anode voltage is increased accordingly, so that an arc discharge between target 1 and anode 4 is ignited and a plasma following the evaporation of target material can be generated, which passes through the anode gap in the direction of the here curved, following the shape of a partial circle, formed absorber electrode 2.
• the absorber electrode 2 is applied to a DC voltage. This voltage at the absorber electrode 2 is above the normal voltage at the anode 4 and the potential of the plasma.
• the absorber electrode 2 can be used to separate the differently charged particles in the ionized particle stream from the plasma. For this purpose, the negatively charged ion particles are removed from the
• Absorber electrode 2 is absorbed and the positively charged particles from the particle stream can move in the direction of the substrate 3 and form the desired virtually particle-free and drop-free layer on its surface. This affects electric field formed between absorber electrode 2 and substrate 3 is only favorable for the desired charge separation and the kinetic energy of the positively charged particles is not additionally increased.
• an electrically negative potential is applied to the substrate 3, which can be favorable for certain purposes.
• the voltage connection to the absorber electrode 2, as can clearly be seen in FIG. 1, is advantageously located on the side of the absorber electrode 2 facing the target 1, as close as possible to the base point of the plasma.
• an aperture 6 can be used, which is arranged between the target 1 and the substrate 3. It only releases a narrowed gap between the diaphragm 6 and the absorber electrode 2 for the passage of the plasma.
• the absorber electrode 2 here consists of a strip carrier 2 ′′, to which individual narrow strips 2 ′ made of electrically conductive material are fastened at a distance from one another. The strips 2 'are aligned so that a reflected ionized particle is reflected away from the substrate.
• a conventional target 1 is used, in which case a negative potential is applied, but this can also be dispensed with.
• a preferably pulsed laser beam 5 is directed onto the target 1 and the plasma is generated from the target material solely with its energy.
• the target 1 can consist of electrically conductive but also of electrically non-conductive material, depending on which layer is to be formed on the substrate 3. Otherwise, this device is designed exactly like the example described in connection with FIG. 3. Of course, embodiments according to the other examples described can also be used, in particular for the formation of the absorber electrode 2.
• a wide variety of layers can be applied to a wide variety of substrates.
• Particle-free aluminum, various aluminum compounds (by adding appropriate reactive gases) and diamond-like carbon layers can be applied.
• a roller-shaped aluminum target 1 is used and the anode 4 for generating the arc discharge in a vacuum and the absorber electrode 2 have the same length as the roller-shaped aluminum target 1.
• an absorber electrode 2 according to FIG. 1 is used, the radius of curvature of which is 60 mm.
• a pulse peak voltage of approx. 400 V is applied to the anode 4 to ignite the vacuum arc discharge.
• the anode voltage is reduced to the arc discharge voltage of approx. 30 V within a few microseconds.
• the current intensity of the arc discharge is approx. 1,000 A, the pulse frequency with which the vacuum arc discharge is carried out is approx. 100 Hz.
• the voltage at the absorber electrode 2 could be kept at average values in the range between 180 V and 200 V and the average current strength at 3 A.
• the isolated substrate suspended in the vacuum chamber In contrast to the exemplary representations, 3 can be kept at ground potential. With such an arrangement, coating rates can be achieved which are achieved at approximately 40%, a procedure without the solution according to the invention, ie without an additional absorber electrode.
• the absorber electrode 2 can also, as in Figure
• strips 2 ' are formed. It is formed from a plurality of flat, planar elements (strips 2 ') arranged at a distance from one another, the individual elements being aligned parallel to one another and the individual elements forming the absorber electrode 2 being aligned orthogonally to the longitudinal direction of the target 1, so that through the gaps between adjacent flat elements in the plasma, any larger droplets that may be present can be removed, and consequently deposition on the substrate 3 can be avoided.
• the flat, flat elements (strips 2 ') of an absorber electrode 2 designed in this way can preferably be shaped on the side facing the plasma, as is shown in the case of the strip carriers 2' 'in FIGS. 3 and 4.
• Elements 2 ' can be connected to spacers arranged at least in one axis, also in an electrically conductive manner.
• the individual strips 2 ' are arranged in a comb-like manner next to one another and are convexly curved.
• each strip 2' has a separate power supply, so that only the strips 2 'are supplied with a correspondingly high enough electrical current which can effectively influence the plasma generated.
• FIG. 5 essentially corresponds to that described above. Only an additional anode 4 is dispensed with and the plasma is generated exclusively with the energy of a laser beam 5, which is deflected along its longitudinal axis while simultaneously rotating the target 1.
• the power supply to the individual strips 2 ′ of the absorber electrode 2 can be controlled accordingly.
• the example shown in FIG. 6 dispenses with an additional anode 4, the function of which is taken over by the absorber electrode 2.
• the arc discharge is therefore initiated by the absorber electrode 2, possibly with the aid of a pulsed laser beam 5.
• the power supply to the absorber electrode 2 is arranged as far as possible from the base point of the plasma, consequently on or in the vicinity of the end face of the absorber electrode 2 pointing in the direction of the substrate 3. The greater the distance, the more favorable is the effect of the absorber electrode 2.

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• Physics & Mathematics (AREA)
• Engineering & Computer Science (AREA)
• Plasma & Fusion (AREA)
• Chemical & Material Sciences (AREA)
• Analytical Chemistry (AREA)
• Physical Vapour Deposition (AREA)
• Application Of Or Painting With Fluid Materials (AREA)

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• 1999
  • 1999-08-20 WO PCT/EP1999/006128 patent/WO2000013201A1/fr active IP Right Grant
  • 1999-08-20 EP EP99941651A patent/EP1110234B1/fr not_active Expired - Lifetime
  • 1999-08-20 US US09/763,636 patent/US6533908B1/en not_active Expired - Lifetime
  • 1999-08-20 AT AT99941651T patent/ATE347735T1/de active
  • 1999-08-20 DE DE59914040T patent/DE59914040D1/de not_active Expired - Lifetime

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